Transplant Surgery - Islet Transplant for Type 1 Diabetes Transplant Surgery » Conditions & Procedures » Islet Transplant for Type 1 Diabetes FOLLOW Sign up for delivery of news Islet Transplant for Type 1 Diabetes Islet cell transplantation places cells from an organ donor into the body of another person. It is used experimentally to treat type 1 diabetes Image Courtesy of UCSF Diabetes Education Online Pancreatic Islets and Beta Cells The pancreas is an organ about the size of a hand located in the abdomen in the vicinity of the stomach, intestines, and other organs. It lies behind the stomach and in front of the spine. The pancreas produce juices that help digest food and hormones such as insulin and glucagon that maintain optimal blood sugar levels and help the body to use and store energy from food. Throughout the pancreas are clusters of cells called the islets of Langerhans. Islets are made up of several types of cells, including beta cells that make insulin. Insulin is a hormone that helps the body use glucose for energy. Insulin and Diabetes Diabetes develops when the body doesn't make enough insulin, cannot use insulin properly, or both, causing glucose to build up in the blood.

Diabetes is a serious disease, which, if not controlled, can be life threatening. It is often associated with long-term complications that can affect every system and part of the body. Diabetes can contribute to eye disorders and blindness, heart disease, stroke, kidney failure, amputation, and nerve damage. Type 1 Diabetes Type 1 diabetes results from the body's failure to produce insulin, the hormone that "unlocks" the cells of the body, allowing glucose to enter and fuel them. It is an autoimmune disease in which the body views the beta cells (insulin producing cells found in the islets of the pancreas) as a foreign substance, so the patient's immune system attacks the islets and kills them. It is estimated that 5-10% of Americans who are diagnosed with diabetes have type 1 diabetes. Most people with type 1 diabetes do not have a family history of the disease and there is no way currently to prevent the onset of type1 diabetes.

Image courtesy of Clinical Islet Transplantation (CIT) Consortium, sponsored by National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK) and National Institute of Allergy and Infectious Diseases (NIAID) Insulin therapy, given by injection or insulin pump, is life-saving. However, it's not perfect. Most people with type 1 diabetes still have blood glucose levels that are above normal. This puts them at risk for the long-term complications of diabetes. Some people have what doctors call labile, or brittle, diabetes. Blood glucose levels swing from high to low despite the best insulin plans. Because of this, long-term type 1 diabetic survivors often develop vascular complications, such as diabetic retinopathy, an eye disease that can cause poor vision and blindness, and diabetic nephropathy, a kidney disease that can lead to kidney failure. Hypoglycemia Unawareness Those who are able to keep their blood glucose levels near normal often have trouble with low blood glucose (hypoglycemia). And after many years, some people lose the early symptoms that warn them that their blood glucose level is dropping.

This is called hypoglycemia unawareness and raises the risk of severe hypoglycemia. Hypoglycemia unawareness is a life-threatening condition that is not easily treatable with medication and is characterized by reduced or absent warning signals for hypoglycemia. Some Type 1 diabetic patients have been known to set their alarms to wake them several times a night out of fear they may have a catastrophic hypoglycemic episode while asleep. For such individuals, transplantation of pancreatic islets is a viable treatment option to consider. Islet Cell Transplantation Procedure In islet transplantation, islets are taken from the pancreas of a deceased organ donor. The islets are purified, processed, and transferred into another person. Once implanted, the beta cells in these islets begin to make and release insulin. Researchers hope that islet transplantation will help people with type 1 diabetes live without daily injections of insulin. Researchers use specialized enzymes to remove islets from the pancreas of a deceased donor. Because the islets are fragile, transplantation occurs soon after they are removed.

Typically a patient receives at least 10,000 islet "equivalents" per kilogram of body weight, extracted from two donor pancreases. Patients often require two transplants to achieve insulin independence. Some transplants have used fewer islet equivalents taken from a single donated pancreas. Transplants are often performed by a radiologist, who uses x rays and ultrasound to guide placement of a catheter-a small plastic tube-through the upper abdomen and into the portal vein of the liver. The islets are then infused slowly through the catheter into the liver. The patient receives a local anesthetic and a sedative. In some cases, a surgeon may perform the transplant through a small incision, using general anesthesia. Islets extracted from a donor pancreas are infused into the liver. Once implanted, the beta cells in the islets begin to make and release insulin. Image courtesy of University of Alberta and the Clinical Islet Transplantation (CIT) Consortium, sponsored by National Institute of Diabetes & Digestive & Kidney Diseases (NIDDK) and National Institute of Allergy and Infectious Diseases (NIAID) Islets begin to release insulin soon after transplantation.

However, full islet function and new blood vessel growth associated with the islets take time. The doctor will order many tests to check blood glucose levels after the transplant, and insulin is usually given until the islets are fully functional. Benefits and Risks Islet Transplantation Benefits The goal of islet transplantation is to infuse enough islets to control the blood glucose level without insulin injections. Other benefits may include improved glucose control and prevention of potentially dangerous episodes of hypoglycemia. Because good control of blood glucose can slow or prevent the progression of complications associated with diabetes, such as heart disease, kidney disease, and nerve or eye damage, a successful transplant may reduce the risk of these complications. Risks Risks of islet transplantation include the risks associated with the transplant procedure-particularly bleeding and blood clots-and side effects from the immunosuppressive drugs that transplant recipients must take to stop the immune system from rejecting the transplanted islets. Most people need two infusions at different times to get enough islets that are working, and some need three. So, even if islet transplantation is found to be effective, currently, there are not enough donor pancreases available to treat everyone with type 1 diabetes.

Immunosuppression and Rejection As with any organ transplant, the recipient of an islet transplant must take drugs every day to keep the body from rejecting the islets. The immune system is programmed to destroy bacteria, viruses, and tissue it recognizes as "foreign," including transplanted islets. In addition, the autoimmune response that destroyed transplant recipients' own islets in the first place can recur and attack the transplanted islets. These drugs put the person at risk for infections and certain cancers. They can also cause side effects that range from mild to severe. Some people who received an islet transplant have had to stop taking these medications, because of side effects and then their new islets stopped working. New Immunosuppression Protocols The Edmonton protocol introduced the use of a new combination of immunosuppressive drugs, also called anti-rejection drugs, including daclizumab (Zenapax), sirolimus (Rapamune), and tacrolimus (Prograf). Daclizumab is given intravenously right after the transplant and then discontinued.

Sirolimus and tacrolimus, the two main drugs that keep the immune system from destroying the transplanted islets, must be taken for life or for as long as the islets continue to function. These drugs have significant side effects and their long-term effects are still not fully known. Immediate side effects of immunosuppressive drugs may include mouth sores and gastrointestinal problems, such as stomach upset and diarrhea. Patients may also have increased blood cholesterol levels, hypertension, anemia, fatigue, decreased white blood cell counts, decreased kidney function, and increased susceptibility to bacterial and viral infections. Taking immunosuppressive drugs also increases the risk of tumors and cancer. Researchers continue to develop and study modifications to the Edmonton protocol drug regimen, including the use of new drugs and new combinations of drugs designed to help reduce destruction of transplanted islets and promote their successful implantation. These therapies may help transplant recipients achieve better function and durability of transplanted islets with fewer side effects. The ultimate goal is to achieve immune tolerance of the transplanted islets, where the patient's immune system no longer recognizes the islets as foreign. If achieved, immune tolerance would allow patients to maintain transplanted islets without long-term immunosuppression.

Researchers are also trying to find new approaches that will allow successful transplantation without the use of immunosuppressive drugs. For example, one study is testing the transplantation of islets that are encapsulated with a special coating designed to prevent rejection. Shortage of Islets A major obstacle to widespread use of islet transplantation is the shortage of islets. Although organs from about 7,000 deceased donors become available each year in the United States, fewer than half of the donated pancreases are suitable for whole organ pancreas transplantation or for harvesting of islets-enough for only a small percentage of those with type 1 diabetes. However, researchers are pursuing various approaches to solve this problem, such as transplanting islets from a single donated pancreas, from a portion of the pancreas of a living donor, or from pigs. Researchers have transplanted pig islets into other animals, including monkeys, by encapsulating the islets or by using drugs to prevent rejection. Another approach is creating islets from other types of cells, such as stem cells. New technologies could then be employed to grow islets in the laboratory.

Note: The information above was reproduced or derived from the following public domain sources: The National Digestive Diseases Information Clearinghouse (NDDIC) , the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) Reference Collection, and MedlinePlus, a service of the National Library of Medicine and National Institutes of Health (NIH), The Clinical Islet Transplantation (CIT) Consortium is a network of clinical centers and a data coordinating center established in 2004 to conduct studies of islet transplantation in patients with type 1 diabetes, also funded by the NIH and NIDDK, and Diabetes Education Online, UCSF Diabetes Teaching Center's Diabetes Education Online. FOLLOW islets of Langerhans | anatomy | Britannica.com Islets of Langerhans Alternative Titles: islands of Langerhans, pancreatic islets Related Topics endocrine system Islets of Langerhans, also called islands of Langerhans, irregularly shaped patches of endocrine tissue located within the pancreas of most vertebrates. They are named for the German physician Paul Langerhans, who first described them in 1869.

The normal human pancreas contains about 1,000,000 islets. The islets consist of four distinct cell types, of which three (alpha, beta, and delta cells) produce important hormones ; the fourth component (C cells) has no known function. The islets of Langerhans are responsible for the endocrine function of the pancreas. Each islet … Encyclopædia Britannica, Inc. The most common islet cell, the beta cell, produces insulin , the major hormone in the regulation of carbohydrate, fat, and protein metabolism. Insulin is crucial in several metabolic processes: it promotes the uptake and metabolism of glucose by the body’s cells; it prevents release of glucose by the liver; it causes muscle cells to take up amino acids, the basic components of protein; and it inhibits the breakdown and release of fats. The release of insulin from the beta cells can be triggered by growth hormone (somatotropin) or by glucagon, but the most important stimulator of insulin release is glucose; when the blood glucose level increases—as it does after a meal—insulin is released to counter it.

The inability of the islet cells to make insulin or the failure to produce amounts sufficient to control blood glucose level are the causes of diabetes mellitus . The islets of Langerhans contain alpha, beta, and delta cells that produce glucagon, insulin, and … Encyclopædia Britannica, Inc. The alpha cells of the islets of Langerhans produce an opposing hormone, glucagon , which releases glucose from the liver and fatty acids from fat tissue. In turn, glucose and free fatty acids favour insulin release and inhibit glucagon release. The delta cells produce somatostatin , a strong inhibitor of somatotropin, insulin, and glucagon; its role in metabolic regulation is not yet clear. Somatostatin is also produced by the hypothalamus and functions there to inhibit secretion of growth hormone by the pituitary gland . Learn More in these related articles: Islet Cells: Islets of Langerhans: Pancreatic Cell What are Islet Cells? The Islets of Langerhans The Islets of Langerhans are commonly referred to as "islets" (pronounced "EYE-lets").

Islets actually are clusters of cells, with each "islet" containing 3,000 to 4,000 cells. Scientists estimate there are 1 million islets in a healthy, adult pancreas. They make up only 1 to 2 percent of the entire organ. Within each islet are several types of cells, which work together to regulate blood sugar. One cell type is the beta cell. Beta cells sense sugar in the blood and release the necessary amount of insulin to maintain normal blood sugar levels. The immune system mistakenly sees beta cells as "potential danger" and destroys them, causing type 1 diabetes . The loss of these cells means the body can no longer produce insulin, the hormone required to convert food into energy for the body’s cells. Although insulin-producing islet cells cease to function in persons with diabetes, the remaining 98 percent of the pancreas continues to function normally, producing digestive enzymes. Here at the DRI, we’re focused on restoring natural insulin production to normalize blood sugar control. One key strategy is islet transplantation -- taking healthy islets from a donor pancreas and transplanting them into patients with diabetes.

We’ve already demonstrated that transplanted islets can function for more than 12 years. Much of our research is now aimed at increasing the supply of islet cells available for transplantation, to find the optimal site for transplantation, as well as eliminating the need for anti-rejection drugs . Islets are clusters of cells scattered throughout the pancreas, which include cells that sense sugar in the blood. Do you know how islet cells are isolated from the pancreas? View this video about the innovative method developed by DRI Director Dr. Camillo Ricordi that makes islet cell transplantation possible. Islets of Langerhans are made of four different cell types. The majority are insulin-producing beta cells (shown in green) and glucagon-producing alpha cells (shown in red). The blue color is a marker used to locate the nucleus of the cells. Using Laser Scanning Cytometry (LSC), DRI scientists can study the physiology of the basic islet components to assess their viability before transplantation. Pancreas - RightDiagnosis.com Pancreas Introduction: Pancreas The pancreas is an internal organ that has two main functions: the release of certain enzymes for digestion, and the release of various endocrine hormones.

The digestive portion that produces digestive enzymes is called the "exocrine pancreas"; the hormone-producing portion is called the "endocrine pancreas". The hormones secreted by the endocrine pancreas are insulin , glucagon , and somatostatin . The cells that secrete insulin are called Islet of Langerhans cells, or more simply just "islet cells". Descriptions of Pancreas Pancreas: A glandular organ located in the abdomen. It makes pancreatic juices, which contain enzymes that aid in digestion, and it produces several hormones, including insulin. The pancreas is surrounded by the stomach, intestines, and other organs. Source: National Institute of Health Pancreas: a large elongated exocrine gland located behind the stomach; secretes pancreatic juice and insulin Source: WordNet 2.1 Pancreas : mixed exocrine and endocrine gland situated transversely across the posterior abdominal wall in the epigastric and hypochondriac regions; endocrine portion is comprised of the islets of Langerhans, and the exocrine portion is a compound acinar gland that secretes digestive enzymes.

Source: CRISP Article Excerpts about Pancreas The pancreas gland, located behind the stomach, releases digestive juices into the intestines and releases key hormones into the bloodstream. Some hormones produced in the islet cells of the pancreas and their effects are: insulin--lowers blood sugar; (Source: excerpt from Multiple Endocrine Neoplasia Type 1: NIDDK ) The pancreas, an organ about the size of a hand, is located behind the lower part of the stomach. It makes insulin and enzymes that help the body use and digest food. Spread all over the pancreas are clusters of cells called the islets of Langerhans. Islets are made up of two types of cells: the alpha cells, which make glucagon, a hormone that raises the level of glucose (sugar) in the blood, and the beta cells, which make insulin. (Source: excerpt from Pancreatic Islet Transplantation: NIDDK ) The pancreas is a gland located deep in the abdomen between the stomach and the spine (backbone). The liver , intestine , and other organs surround the pancreas. The pancreas is about 6 inches long and is shaped like a flat pear.

The widest part of the pancreas is the head, the middle section is the body, and the thinnest part is the tail. (Source: excerpt from What You Need To Know About Cancer of the Pancreas: NCI ) Summary Information: Pancreas Pancreas: The pancreas is an organ of the endocrine system and also an accessory and exocrine organ of the digestive system. It is located in the upper left area of the abdominal cavity. The pancreas has a variety of functions, including producing the pancreatic hormones glucagon, insulin, and somatostatin. These pancreatic hormones exert a variety of effects on the body's metabolism and help to regulate glucose and energy. The pancreas also secretes pancreatic juice, which helps to break down chyme in the small intestine during digestion. The pancreas includes the islets of Langerhans, alpha cells, beta cells, delta cells, and pancreatic acini. Conditions that can afflict the pancreas include pancreatic cancer, type 1 diabetes, type 2 diabetes, pancreatitis, cystic fibrosis, and trauma.

Closely Related Organs: Pancreas Types of Cells in the Pancreas About Watch and Favorite Watch Watching this resources will notify you when proposed changes or new versions are created so you can keep track of improvements that have been made. Favorite Favoriting this resource allows you to save it in the “My Resources” tab of your account. There, you can easily access this resource later when you’re ready to customize it or assign it to your students. Types of Cells in the Pancreas The islets of Langerhans are the regions of the pancreas that contain many hormone-producing endocrine cells. Learning Objective Distinguish between the cell types of the pancreas Key Points The pancreas reveals two different types of parenchymal tissue : exocrine acini ducts and the endocrine islets of Langerhans . The hormones produced in the islets of Langerhans are insulin , glucagon , somatostatin , pancreatic polypeptide, and ghrelin. The pancreatic hormones are secreted by alpha, beta, delta, gamma, and epsilon cells . Terms Full Text Pancreatic Cells The pancreas is a glandular organ that belongs to both the digestive and the endocrine systems of vertebrates.

It is an endocrine gland that produces several important hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide. It is also a digestive, exocrine organ, that secretes pancreatic juice that contains digestive enzymes to assist with digestion and the absorption of nutrients in the small intestine . These enzymes help to further break down the carbohydrates , proteins , and lipids in the chyme . Under a microscope, stained sections of the pancreas reveal two different types of parenchymal tissue. The light-stained clusters of cells are called islets of Langerhans, which produce hormones that underlie the endocrine functions of the pancreas. The dark-stained cells form acini, connected to ducts. Acinar cells belong to the exocrine pancreas and secrete digestive enzymes into the gut via a system of ducts. This is a microscope photograph of a porcine islet of Langerhans. On the left is a brightfield image created using hematoxylin stain; nuclei are dark circles and the acinar pancreatic tissue is darker than the islet tissue. The right image is the same section stained by immunofluorescence against insulin, indicating beta cells.

Islets of Langerhans The pancreatic islets are small islands of cells that produce hormones that regulate blood glucose levels. Hormones produced in the pancreatic islets are secreted directly into the blood flow by five different types of cells. The endocrine cell subsets are: Alpha cells that produce glucagon, and make up 15–20% of total islet cells. Glucagon is a hormone that raises blood glucose levels by stimulating the liver to convert its glycogen into glucose. Beta cells that produce insulin and amylin, and make up 65–80% of the total islet cells. Insulin lowers blood glucose levels by stimulating cells to take up glucose out of the blood stream. Amylin slows gastric emptying, preventing spikes in blood glucose levels. Delta cells that produce somatostatin, and make up 3–10% of the total islet cells. Somatostatin is a hormone that suppresses the release of the other hormones made in the pancreas. Gamma cells that produce pancreatic polypeptide, and make up 3–5% of the total islet cells. Pancreatic polypeptide regulates both the endocrine and exocrine pancreatic secretions.

Epsilon cells that produce ghrelin, and make up less than 1% of the total islet cells. Ghrelin is a protein that stimulates hunger. The islets of Langerhans can influence each other through paracrine and autocrine communication. The paracrine feedback system is based on the following correlations: The insulin hormone activates beta cells and inhibits alpha cells. The hormone glucagon activates alpha cells which then activate beta cells and delta cells. Somatostatin hormone inhibits alpha cells and beta cells. Anatomy and Physiology of Animals/Body Organisation - Wikibooks, open books for an open world Anatomy and Physiology of Animals/Body Organisation From Wikibooks, open books for an open world Jump to: navigation , search original image by grrphoto cc by In this chapter, the way the cells of the body are organised into different tissues is described. You will find out how these tissues are arranged into organs, and how the organs form systems such as the digestive system and the reproductive system. Also in this chapter, the important concept of homeostasis is defined. You are also introduced to those pesky things -- directional terms.

Contents After completing this section, you should know: the “Mrs Gren” characteristics of living organisms what a tissue is four basic types of tissues, their general function and where they are found in the body the basic organisation of the body of vertebrates including the main body cavities and the location of the following major organs: thorax, heart, lungs, thymus, abdomen, liver, stomach, spleen, intestines, kidneys, sperm ducts, ovaries, uterus, cervix, vagina, urinary bladder the 11 body systems what homeostasis is directional terms including dorsal, ventral, caudal, cranial, medial, lateral, proximal, distal, rostral, palmar and plantar. Plus transverse and longitudinal sections The Organisation Of Animal Bodies[ edit ] Living organisms move, feed, respire (burn food to make energy), grow, sense their environment, excrete and reproduce. These seven characteristics are sometimes summarized by the words “MRS GREN”. functions of: Movement Excretion Nutrition Living organisms are made from cells which are organised into tissues and these are themselves combined to form organs and systems. Skin cells, muscle cells, skeleton cells and nerve cells, for example.

These different types of cells are not just scattered around randomly but similar cells that perform the same function are arranged in groups. These collections of similar cells are known as tissues. There are four main types of tissues in animals. These are: Epithelial tissues that form linings, coverings and glands, Connective tissues for transport and support Muscle tissues for movement and Nervous tissues for carrying messages. Epithelial Tissues[ edit ] Epithelium (plural epithelia) is tissue that covers and lines. It covers an organ or lines a tube or space in the body. There are several different types of epithelium, distinguished by the different shapes of the cells and whether they consist of only a single layer of cells or several layers of cells. Simple Epithelia - with a single layer of cells[ edit ] Diagram 4.1: Squamous epithelium Squamous epithelium[ edit ] Squamous epithelium consists of a single layer of flattened cells that are shaped rather like ‘crazy paving’. It is found lining the heart, blood vessels, lung alveoli and body cavities (see diagram 4.1). Its thinness allows molecules to diffuse across readily.

Diagram 4.2: Cuboidal epithelium Cuboidal epithelium[ edit ] Cuboidal epithelium consists of a single layer of cube shaped cells. It is rare in the body but is found lining kidney tubules (see diagram 4.2). Molecules pass across it by diffusion, osmosis and active transport. Diagram 4.3: Columnar epithelium Columnar epithelium[ edit ] Columnar epithelium consists of column shaped cells. It is found lining the gut from the stomach to the anus (see diagram 4.3). Digested food products move across it into the blood stream. Diagram 4.4: Columnar epithelium with cilia Columnar epithelium with cilia[ edit ] Columnar epithelium with cilia on the free surface (also known as the apical side of the cell) lines the respiratory tract, fallopian tubes and uterus (see diagram 4.4). The cilia beat rhythmically to transport particles. Diagram 4.5: Transitional epithelium Transitional epithelium - with a variable number of layers[ edit ] The cells in transitional epithelium can move over one another allowing it to stretch.

It is found in the wall of the bladder (see diagram 4.5). Stratified epithelia - with several layers of cells[ edit ] Diagram 4.6: Stratified squamous epithelium Epithelia with several layers of cells are found where toughness and resistance to abrasion are needed. Stratified squamous epithelium[ edit ] Stratified squamous epithelium has many layers of flattened cells. It is found lining the mouth, cervix and vagina. Cells at the base divide and push up the cells above them and cells at the top are worn or pushed off the surface (see diagram 4.6). This type of epithelium protects underlying layers and repairs itself rapidly if damaged. Keratinised stratified squamous epithelium[ edit ] Keratinised stratified squamous epithelium has a tough waterproof protein called keratin deposited in the cells. It forms the skin found covering the outer surface of mammals. (Skin will be described in more detail in Chapter 5). Connective Tissues[ edit ] Blood, bone, tendons, cartilage, fibrous connective tissue and fat (adipose) tissue are all classed as connective tissues.

They are tissues that are used for supporting the body or transporting substances around the body. They also consist of three parts: they all have cells suspended in a ground substance or matrix and most have fibres running through it. Blood[ edit ] Blood consists of a matrix - plasma, with several types of cells and cell fragments suspended in it. The fibres are only evident in blood that has clotted. Blood will be described in detail in chapter 8. Lymph[ edit ] Lymph is similar in composition to blood plasma with various types of white blood cell floating in it. It flows in lymphatic vessels. Connective tissue ‘proper’[ edit ] Diagram 4.7: Loose connective tissue Connective tissue 'proper' consists of a jelly-like matrix with a dense network of collagen and elastic fibres and various cells embedded in it. There are various different forms of ‘proper’ connective tissue (see 1, 2 and 3 below). Loose connective tissue[ edit ] Loose connective tissue is a sticky whitish substance that fills the spaces between organs. It is found in the dermis of the skin (see diagram 4.7).

Dense connective tissue[ edit ] Dense connective tissue contains lots of thick fibres and is very strong. It forms tendons, ligaments and heart valves and covers bones and organs like the kidney and liver. Adipose tissue[ edit ] Adipose tissue consists of cells filled with fat. It forms the fatty layer under the dermis of the skin, around the kidneys and heart and the yellow marrow of the bones. Diagram 4.8: Cartilage Cartilage[ edit ] Cartilage is the ‘gristle’ of the meat. It consists of a tough jelly-like matrix with cells suspended in it. It may contain collagen and elastic fibres. It is a flexible but tough tissue and is found at the ends of bones, in the nose, ear and trachea and between the vertebrae (see diagram 4.8). Bone[ edit ] Bone consists of a solid matrix made of calcium salts that give it its hardness. Collagen fibres running through it give it its strength. Bone cells are found in spaces in the matrix. Two types of bone are found in the skeleton namely spongy and compact bone. They differ in the way the cells and matrix are arranged.

(See Chapter 6 for more details of bone). Muscle Tissues[ edit ] Muscle tissue is composed of cells that contract and move the body. There are three types of muscle tissue: Diagram 4.9: Smooth muscle fibres Smooth muscle[ edit ] Smooth muscle consists of long and slender cells with a central nucleus (see diagram 4.9). It is found in the walls of blood vessels, airways to the lungs and the gut. It changes the size of the blood vessels and helps move food and fluid along. Contraction of smooth muscle fibres occurs without the conscious control of the animal. Diagram 4.10: Skeletal muscle fibres Skeletal muscle[ edit ] Skeletal muscle (sometimes called striated, striped or voluntary muscle) has striped fibres with alternating light and dark bands. It is attached to bones and is under the voluntary control of the animal (see diagram 4.10). Diagram 4.11: Cardiac muscle fibres Cardiac muscle[ edit ] Cardiac muscle is found only in the walls of the heart where it produces the ‘heart beat’. Cardiac muscle cells are branched cylinders with central nuclei and faint stripes (see diagram 4.11).

Each fibre contracts automatically but the heart beat as a whole is controlled by the pacemaker and the involuntary autonomic nervous system. Diagram 4.12: A motor neuron Nervous Tissues[ edit ] Nervous tissue forms the nerves, spinal cord and brain. Nerve cells or neurons consist of a cell body and a long thread or axon that carries the nerve impulse. An insulating sheath of fatty material (myelin) usually surrounds the axon. Diagram 4.12 shows a typical motor neuron that sends messages to muscles to contract. Vertebrate Bodies[ edit ] We are so familiar with animals with backbones (i.e. vertebrates) that it seems rather unnecessary to point out that the body is divided into three sections. There is a well-defined head that contains the brain, the major sense organs and the mouth, a trunk that contains the other organs and a well-developed tail. Other features of vertebrates may be less apparent. For instance, vertebrates that live on the land have developed a flexible neck that is absent in fish where it would be in the way of the gills and interfere with streamlining.

Mammals but not other vertebrates have a sheet of muscle called the diaphragm that divides the trunk into the chest region or thorax and the abdomen. Body Cavities[ edit ] Diagram 4.13: The body cavities In contrast to many primitive animals, vertebrates have spaces or body cavities that contain the body organs. Most vertebrates have a single body cavity but in mammals the diaphragm divides the main cavity into a thoracic and an abdominal cavity. In the thoracic cavity the heart and lungs are surrounded by their own membranes so that cavities are created around the heart - the pericardial cavity, and around the lungs – the pleural cavity (see diagram 4.13). Organs[ edit ] Diagram 4.14: Cells, tissues and organs forming the digestive system Just as the various parts of the cell work together to perform the cell’s functions and a large number of similar cells make up a tissue, so many different tissues can “cooperate” to form an organ that performs a particular function. For example, connective tissues, epithelial tissues, muscle tissue and nervous tissue combine to make the organ that we call the stomach.

In turn the stomach combines with other organs like the intestines, liver and pancreas to form the digestive system (see diagram 4.14). Generalised Plan Of The Mammalian Body[ edit ] Diagram 4.15: The main organs of the vertebrate body At this point it would be a good idea to make yourself familiar with the major organs and their positions in the body of a mammal like the rabbit. Diagram 4.15 shows the main body organs. Body Systems[ edit ] Organs do not work in isolation but function in cooperation with other organs and body structures to bring about the MRS GREN functions necessary to keep an animal alive. For example the stomach can only work in conjunction with the mouth and oesophagus (gullet). These provide it with the food it breaks down and digests. It then needs to pass the food on to the intestines etc. for further digestion and absorption. The organs involved with the taking of food into the body, the digestion and absorption of the food and elimination of waste products are collectively known as the digestive system. The 11 body systems[ edit ] Skin The skin covering the body consists of two layers, the epidermis and dermis.

Associated with these layers are hairs, feathers, claws, hoofs, glands and sense organs of the skin. Skeletal System This can be divided into the bones of the skeleton and the joints where the bones move over each other. Muscular System The muscles, in conjunction with the skeleton and joints, give the body the ability to move. Cardiovascular System This is also known as the circulatory system. It consists of the heart, the blood vessels and the blood. It transports substances around the body. Lymphatic System This system is responsible for collecting and “cleaning” the fluid that leaks out of the blood vessels. This fluid is then returned to the blood system. The lymphatic system also makes antibodies that protect the body from invasion by bacteria etc. It consists of lymphatic vessels, lymph nodes, the spleen and thymus glands. Respiratory System This is the system involved with bringing oxygen in the air into the body and getting rid of carbon dioxide, which is a waste product of processes that occur in the cell. It is made up of the trachea, bronchi, bronchioles, lungs, diaphragm, ribs and muscles that move the ribs in breathing.

Digestive System This is also known as the gastrointestinal system, alimentary system or gut. It consists of the digestive tube and glands like the liver and pancreas that produce digestive secretions. It is concerned with breaking down the large molecules in foods into smaller ones that can be absorbed into the blood and lymph. Waste material is also eliminated by the digestive system. Urinary System This is also known as the renal system. It removes waste products from the blood and is made up of the kidneys, ureters and bladder. Reproductive System This is the system that keeps the species going by making new individuals. It is made up of the ovaries, uterus, vagina and fallopian tubes in the female and the testes with associated glands and ducts in the male. Nervous System This system coordinates the activities of the body and responses to the environment. It consists of the sense organs (eye, ear, semicircular canals, and organs of taste and smell), the nerves, brain and spinal cord. Endocrine System This is the system that produces chemical messengers or hormones.

It consists of various endocrine glands (ductless glands) that include the pituitary, adrenal, thyroid and pineal glands as well as the testes and ovary. Homeostasis[ edit ] All the body systems, except the reproductive system, are involved with keeping the conditions inside the animal more or less stable. This is called homeostasis. These constant conditions are essential for the survival and proper functioning of the cells, tissues and organs of the body. The skin, for example, has an important role in keeping the temperature of the body constant. The kidneys keep the concentration of salts in the blood within limits and the islets of Langerhans in the pancreas maintain the correct level of glucose in the blood through the hormone insulin. As long as the various body processes remain within normal limits, the body functions properly and is healthy. Once homeostasis is disturbed disease or death may result. (See Chapters 12 and16 for more on homeostasis). Diagram 4.16: The directional terms used with animals Diagram 4.17: Transverse and longitudinal sections of a mouse In the following chapters the systems of the body in the list above will be covered one by one.

For each one the structure of the organs involved will be described and the way they function will be explained. In order to describe structures in the body of an animal it is necessary to have a system for describing the position of parts of the body in relation to other parts. For example it may be necessary to describe the position of the liver in relation to the diaphragm, or the heart in relation to the lungs. Certainly if you work further with animals, in a veterinary clinic for example, it will be necessary to be able to accurately describe the position of an injury. The terms used for this are called directional terms. The most common directional terms are right and left. However, even these are not completely straightforward especially when looking at diagrams of animals. The convention is to show the left side of the animal or organ on the right side of the page. This is the view you would get looking down on an animal lying on its back during surgery or in a post-mortem. Sometimes it is useful to imagine ‘getting inside’ the animal (so to speak) to check which side is which. The other common and useful directional terms are listed below and shown in diagram 4.16.

Term The "walking" surface of the hind paw The pads are on the plantar side of the foot Note that we don’t use the terms superior and inferior for animals. They are only used to describe the position of structures in the human body (and possibly apes) where the upright posture means some structures are above or superior to others. In order to look at the structure of some of the parts or organs of the body it may be necessary to cut them open or even make thin slices of them that they can be examined under the microscope. The direction and position of slices or sections through an animal’s body have their own terminology. If an animal or organ is sliced lengthwise this section is called a longitudinal or sagittal section. This is sometimes abbreviated to LS. If the section is sliced crosswise it is called a transverse or cross section. This is sometimes abbreviated to TS or XS (see diagram 4.17). 4. Name the body system that... a) includes the bones and joints: b) includes the ovaries and testes: c) produces hormones: d) includes the heart, blood vessels and blood: 5. What is homeostasis? 6.

Circle which is correct: a) The head is cranial | caudal to the neck b) The heart is medial | lateral to the ribs c) The elbow is proximal | distal to the fingers d) The spine is dorsal | ventral to the heart 7. Indicate whether or not these statements are true. a) The stomach is cranial to the diaphragm - true | false b) The heart lies in the pelvic cavity - true | false c) The spleen is roughly the same size as the stomach and lies near it - true | false d) The small intestine is proximal to the kidneys - true | false e) The bladder is medial to the hips - true | false f) The liver is cranial to the heart - true | false Websites[ edit ] Animal organ systems and homeostasis Overview of the different organ systems (in humans) and their functions in maintaining homeostasis in the body.

Islets of Langerhans - RightDiagnosis.com Islets of Langerhans Introduction: Islets of Langerhans Description of Islets of Langerhans Islets of Langerhans: cell clusters in the pancreas that form the endocrine part of that organ; secrete insulin and other hormones. Source: WordNet 2.1 Islets of Langerhans: Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the PANCREAS among the exocrine acini. Each islet is surrounded by connective tissue fibers and penetrated by a network of capillaries. There are four major cell types. The most abundant beta cells (50-80%) secrete INSULIN . Alpha cells (5-20%) secrete GLUCAGON . PP cells (10-35%) secrete PANCREATIC POLYPEPTIDE . Delta cells (~5%) secrete SOMATOSTATIN .

Source: MeSH 2007 Islets of Langerhans: Related Topics These medical condition or symptom topics may be relevant to medical information for Islets of Langerhans: Homeostasis - blood sugar and temperature Homeostasis - blood sugar and temperature Select from our full list of topics... A Home / Homeostasis - blood sugar and temperature Homeostasis - blood sugar and temperature 14-16 The temperature in the core of the body; not at the surface of the skin Blood sugar The sugar (glucose) dissolved in the blood; the normal range is 4.0 - 7.8 mmol/l Puberty The time of gradual development of the secondary sexual characteristics and sexual maturity. Insulin A hormone produced by the pancreas. It allows cells in the body to take in and store glucose. Homeostasis The maintenance of a constant internal environment in the body Glucose A type of sugar: a mono saccharide with 6 carbon atoms (a hexose sugar). Glucagon A hormone produced by the pancreas. It causes the liver to convert glycogen back to glucose and to release glucose into the bloodstream. Glossary A list of often difficult or specialised words with their definitions.

Enzymes Reusable protein molecules which act as biological catalysts, changing the rate of chemical reactions in the body without being affected themselves Cells The basic unit from which all living organisms are built up, consisting of a cell membrane surrounding cytoplasm and a nucleus. Homeostasis - Sugar balance and temperature control Homeostasis describes the functions of your body which work to keep your internal environment constant within a very narrow range. Two important aspects of homeostasis are balancing the blood sugar levels and maintaining the body temperature. Your body is made up of millions of cells which need the conditions inside your body to be as constant as possible so they can work properly. However everything you do tends to change your internal conditions. You take millions of new molecules into your body when you eat and digest food. Your blood sugar levels soar after you have a meal - but your cells use up the glucose fast when you exercise hard. You release heat energy every time you move about, the amount of water you take into and lose from your body varies all the time and your cells are constantly producing poisonous waste (see Homeostasis - the kidneys and water balance .) The blood sugar levels in your body are coordinated by hormones, chemicals which regulate and balance the working of organs and cells.

Hormones are made in endocrine glands and are carried around the body to their target organs in the blood stream. Some hormones have long term effects, for example, the hormones that control how you grow and the changes that happen at puberty. Other hormones have shorter term effects. The hormones insulin and glucagon which control your blood sugar levels are like this. It is important that the core temperature of your body stays within a very small range for the enzymes in the cells of your body to work properly. Your skin is one of the most important organs in the control of body temperature. Contents

Question: In which organ of the body would you find the 'Islets of Langerhans'?
Answer: PANCREAS